Problem: $ D = \left[\begin{array}{rr}1 & 9 \\ 9 & 0\end{array}\right]$ What is $ D^{T}$ ?
To find the transpose, swap the rows and columns. $ D^{T}$ = $\left[\begin{array}{rr}1 & 9 \\ 9 & 0\end{array}\right]$